1. Field of the Invention
The present invention relates to a magneto-optical recording medium having a two-layer magnetic film recording layer for recording information by radiation of light beam. The present invention also relates to a recording method using the same.
2. Related Background Art
Research and development of an optical memory element which uses a laser beam to realize a high density and large capacity memory have been accomplished rapidly. Magneto-optical recording media is one of the favored medium used as rewritable optical memory elements.
Of course, when information recorded on such a magneto optical recording medium is to be re-written, the information should be erased and then new information should be recorded. However, overwriting of information in magneto-optical media cannot be attained. For example, when information on a predetermined track on a magnetooptical disk is to be rewritten, the information on the track must first be erased in one revolution of the disk and then new information is written in the next revolution. As a result, the re-recording speed is low.
In order to solve the above-mentioned problem, separate record/reproduce and erase heads can be provided, or information can be recorded while a magnetic field applied while a continuous laser beam is modulated. However, such an apparatus is of large scale and high cost, and may also not attain high speed modulation.
On the other hand, the present inventors already proposed in European Patent Application Publication No. 258,978 (corresponding to copending U.S. patent application Ser. No. 475,941, filed Jan. 30, 1990), an overwritable magnetooptical recording medium which is not associated with the above-mentioned drawbacks of the prior art and a recording method using the same. Such medium is provided with a first vertical magnetic layer and a second vertical magnetic layer of a higher Curie temperature and a lower coercive force than those of the first vertical magnetic layer, which are laminated in succession and are mutually exchange coupled. The application also describes a structure including a regulation layer provided between the first and second vertical magnetic layers serving to regulate the exchange force therebetween. The regulation layer comprises a magnetic film exhibiting in-plane magnetic anisotropy at room temperature and vertical magnetic anisotropy at an elevated temperature.